Fuel injection pump for internal combustion engines

Abstract

The invention relates to a fuel injection pump for internal combustion engines, having a pump piston guided in a cylinder bore of a pump body, which pump piston defines a pump work chamber in the cylinder bore and which is axially driven by a cam drive counter to the force of a restoring spring. Each individual cylinder of the engine to be fed is assigned a fuel injection pump, which is inserted into a bore in the engine housing; at the same time, the engine housing serves as the pump housing. In order to limit frictional wear, which is caused by the back-and-forth motion of the roller tappet of the cam drive guided in the engine housing and to easily replace pump parts, a thin-walled slide bush is disposed between the roller tappet and the housing bore. The slide bush is fastened with radial play on the pump body and additionally prevents the roller tappet from slipping out and prevents the preassembled fuel injection pump from falling apart when it is not installed in the housing bore.

What is claimed and desired to be secured by Letters Patent of the United States is: 
     
       1. A fuel injection pump for internal combustion engines that supplies fuel to an individual injection valve associated with a cylinder of the internal combustion engine, having a pump body (3) which is inserted into a bore (2) in a housing (1) of the engine, said pump body includes a cylinder bore (5), a pump piston (7), guided in the cylinder bore of the pump body, said pump piston encloses a pump work chamber (11) in said cylinder bore, said pump piston (7) is axially set in motion by a cam drive (15) provided in the engine housing (1) via a roller tappet (19), which is guided in the engine housing (1) and secured against torsion, counter to a force of a restoring spring (17) which is supported on the pump body (3) and the roller tappet (19), the roller tappet (19) is guided in a slide bush (29), which is introduced between said roller tappet and the engine housing (1), said slide bush is inserted into the housing bore (2) and is fastened so that the slide bush does not rotate, said slide bush also encompasses the restoring spring (17) and a part of the pump body (3), and a bolt (43) extending into said tappet includes a head which slides in a longitudinal slit (41) in said slide bush (29), said bolt (43) and longitudinal slit connection connects the roller tappet (19) in the slide bush (29), to fix the rotational position of the roller tappet (19) relative to the cam drive (15). 
     
     
       2. A fuel injection pump according to claim 1, in which the slide bush (29) has an axially oriented stop, by means of which the displaceability of the roller tappet (19) is defined and influenced by the force of the restoring spring (17), wherein the restoring spring (17) is inserted, with initial tension, between the pump body (3) and the roller tappet (19). 
     
     
       3. A fuel injection pump according to claim 2, in which the bolt (43) is inserted into said roller tappet perpendicular to an axis of the pump piston, said bolt prevents torsion, by engaging said longitudinal slit (41), which is closed on opposite ends, in the slide bush (29), wherein one end of the longitudinal slit (41) serves as an axial stop for the bolt (43) and the roller tappet (19). 
     
     
       4. A fuel injection pump according to claim 3, in which the slide bush (29) is embodied as a tube and is fastened on the pump body (3) with radial play, wherein the restoring spring (17) is supported on the pump body (3). 
     
     
       5. A fuel injection pump according to claim 2, in which the slide bush (29) has an axial stop supported by a wire ring (67) guided in an annular groove, and the slide bush (29) extends axially to a height of a roller bolt (21), which carries the roller (23) in the roller tappet (19) and penetrates the roller tappet (19) transversely to its longitudinal axis. 
     
     
       6. A fuel injection pump according to claim 5, in which the roller bolt (21) has ends (63), with which it is guided in longitudinal slits (61) in the slide bush (29) that form a guide. 
     
     
       7. A fuel injection pump according to claim 2, in which the slide bush (29) has a tab (65) angled inward on an interior of an end remote from the pump body (3) which functions as an axial stop, and the slide bush (29) extends axially to a height of a roller bolt (21), which carries the roller (23) in the roller tappet (19) and penetrates the roller tappet (19) transversely to its longitudinal axis. 
     
     
       8. A fuel injection pump according to claim 7, in which the slide bush (29) is embodied as a tube and is fastened on the pump body (3) with radial play, wherein the restoring spring (17) is supported on the pump body (3). 
     
     
       9. A fuel injection pump according to claim 7, in which the roller bolt (21) has ends (63), with which it is guided in longitudinal slits (61) in the slide bush (29) that form a guide. 
     
     
       10. A fuel injection pump according to claim 9, in which the slide bush (29) is embodied as a tube and is fastened on the pump body (3) with radial play, wherein the restoring spring (17) is supported on the pump body (3). 
     
     
       11. A fuel injection pump according to claim 2, in which in the region of the roller tappet (19), the slide bush (29) has a radial bore (71) into which a cylindrical disk (73) is inserted as a guide piece, said cylindrical disk (73) is pressed inwardly by means of a wire ring (75) guided in an external annular groove (77) on the slide bush (29) against a flattened, rectangular, planar recess (79) on the roller tappet (19) that the cylindrical disk extends in the direction of the axis of the pump piston, wherein the horizontal edges of said recess (79) function as a stop which defines an axial travel of the roller tappet (19) in the slide bush (29) and the vertical edges serve to fix the rotational position of the roller tappet (19). 
     
     
       12. A fuel injection pump according to claim 11, in which the slide bush (29) is embodied as a tube and is fastened on the pump body (3) with radial play, wherein the restoring spring (17) is supported on the pump body (3). 
     
     
       13. A fuel injection pump according to claim 11, in which the cylindrical disk (73) has an internal thread and means by which a tool can engage said cylindrical disk to remove it from the bore (71). 
     
     
       14. A fuel injection pump according to claim 13, in which the restoring spring (17) is supported at one end on the roller tappet (19) and is axially supported on another end on a flange ring (39), which contacts the pump body (3) and is disposed in the slide bush (29). 
     
     
       15. A fuel injection pump according to claim 1, in which the slide bush (29) is embodied as a pipe having thin walls, which is inherently stable with reference to forces exerted during installation and which is secured against tensile strain by means of the restoring spring (17) with initial tension, and which is inserted, with tight sliding play, between a region that receives the roller tapper (19) and the wall of the housing bore (2). 
     
     
       16. A fuel injection pump according to claim 15, in which the slide bush (29) is embodied as a tube and is fastened on the pump body (3) with radial play, wherein the restoring spring (17) is supported on the pump body (3). 
     
     
       17. A fuel injection pump according to claim 12, in which the connection between the slide bush (29) and the pump body (3) is effected via a collared bolt (51) inserted into the pump body (3) along the axis of the pump piston and guided in a flange ring (39) by means of a bore (53), and the rotational position of the slide bush (29) relative to the pump body (3) is fixed by means of a drift pin (55). 
     
     
       18. A fuel injection pump according to claim 1, in which the slide bush (29) is embodied as a thin-walled pipe that is slit axially along its entire length, which is inserted in the housing bore (2) of the fuel injection pump and is braced axially against the pump body (3) via a flanged portion (99), which protrudes from the housing bore (2). 
     
     
       19. A fuel injection pump according to claim 18, in which the slide bush (29) is embodied as a tube and is fastened on the pump body (3) with radial play, wherein the restoring spring (17) is supported on the pump body (3). 
     
     
       20. A fuel injection pump according to claim 1, in which the slide bush (29) is connected to the pump body (3) by means of a bolt (33) inserted radially in the pump body (3) and which protrudes into a bore (31) in the slide bush (29), and in a predetermined rotational position is affixed to the pump body (3) by means of a drift pin (37). 
     
     
       21. A fuel injection pump according to claim 1, in which the injection control is effected via a magnet valve (91) that communicates with the pump work chamber (11) by means of a fuel line (13). 
     
     
       22. A fuel injection pump according to claim 21, in which the magnet valve (91) is disposed in line with, parallel to the axis of, and directly on the pump body (3), and the cylinder bore (5), which defines the pump work chamber (11), is embodied as a blind bore from which a high-pressure connection (93), which is embodied on a side of the pump body (3), extends laterally.